1. Field
Aspects of embodiments of the present invention relate to a display device.
2. Description of the Related Art
Display devices, such as a liquid crystal display (LCD), an organic light emitting diode display (OLED display), and an electrophoretic display, include a display panel in which an electro-optical active layer and a pixel electrode are formed. For example, the organic light emitting diode display includes an organic emission layer as the electro-optical active layer and the liquid crystal display includes an liquid crystal layer as the electro-optical active layer. The pixel electrode may be connected to a switching device such as a thin film transistor to receive a data signal, and the electro-optical active layer converts the data signal into an optical signal to display an image.
Among those, the organic light emitting diode display is a display device that uses an organic light emitting diode, which is a self light emitting device, to display an image. Therefore, the organic light emitting diode display does not require a separate light source and therefore is excellent in power consumption, response speed, viewing angle, and contrast ratio. Further, the organic light emitting diode display may be slimmed, may have excellent luminance and color purity, and may be applied to a flexible display device.
The organic light emitting diode display includes a pixel electrode, a counter electrode, and an emission layer positioned therebetween. One of the pixel electrode and the counter electrode is an anode and the other thereof is a cathode. The organic light emitting diode display combines electrons injected from the cathode with holes injected from the anode in the light emitting layer to form excitons and emits light while the excitons emits energy. The counter electrode is formed over a plurality of pixels and may be applied with a constant common voltage.
When impurities such as moisture and oxygen flow from the outside into the display device, the life of electric devices including the display device may be shortened and the organic light emitting diode display may have reduced emission efficiency of the emission layer. Further, a problem of a change in an emission color of the emission layer, etc., may occur.
Therefore, encapsulation processing to isolate the electric devices in the display device from the external environment at the time of manufacturing the display device to prevent impurities such as moisture from penetrating is performed. As the encapsulation processing method, there are a method for laminating a layer made of organic polymers such as polyester (PET) on an upper part of a lower substrate on which a thin film transistor, an emission layer, and the like are formed, a method for forming a cover or a cap with an encapsulating substrate and encapsulating edges of the lower substrate and the encapsulating substrate with a sealant, a method for forming an encapsulating portion including an encapsulating thin film layer formed by laminating a plurality of thin films instead of the encapsulating substrate, etc. A layer or a member that performs an encapsulating function is called an encapsulating portion.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not constitute prior art.